I had a few Erythrina bidwilli when I lived in AZ. I love this plant and they are excellent hummingbird attractors. I am pretty sure they are only hardy to zone 9 though (25 degrees).
If we are talking about the same plant...this some hardiness info from a very reputable nursery in AZ that I had much luck with run by an old professor of horiticultre at U of A:
http://www.aridzonetrees.com/AZT%20Interactive%20Buttons/Tree%20Index/Cut%20sheets/Erythrina/Erythrina%20bidwillii.htm

They do freeze back but they flower on last year's wood so if they freeze too hard and don't have any stem tissue left they won't bloom (i.e. their roots are probably hardy here but you won't get any flowers). Also to get the cool (but poisionus) beans to set you need two plants.

Kam, thanks for the input. It sounds like personal experience contradicts the claims of the OK nursery that I've been checking out:

"A hybrid usually listed hardy to zone 8, it has survived every winter in our zone 6b garden since I planted it in 2000. Its shrubby branches die back to the ground each winter, but with each new spring come new sprouts from the root which are later topped with those incredible flowers."

Even if their experience of getting flowers on new wood is true, there is a good chance it requires their summer weather growing conditions, which are vastly different than our's in the PNW.